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ISTANBUL TECHNICAL UNIVERSITY DEPARTMENT OF GEOMATICS ENGINEERING

Prof. Dr. Ergin TARItranslated by Res. Assist. Serpil ATEŞ

Please NOTE

Following notes of Engineering Surveying lecture are composed as of Baykal 2009 by preserving numbering

on sections, figures and equations with slight changes on subscripts and notations (such as T->TO T’->TF) in

general.

Baykal 2009: Baykal, O., Mühendislik Ölçmeleri 1,Metinler (in Turkish), Birsen Yayınevi, ISBN: 978-975-511-524-5, İstanbul, 2009.

ISTANBUL TECHNICAL UNIVERSITY DEPARTMENT OF GEOMATICS ENGINEERING

Prof. Dr. Ergin TARItranslated by Res. Assist. Serpil ATEŞ

TRANSPORTATION and TRANSPORTATION STRUCTURES –

GENERAL DEFINITIONSTransportation, Transportation Structure: Transportation is explained asthe phenomena of replacement of living creatures (human andanimal) andgoods (solid, liquid, gas) and energy with respect to human demand andbenefit. Man-made engineering structures serve for transportation are calledtransportation structures [Müller, 1984, p.8]. According to this definition, allhighway, rail, water and air transportation systems; liquid and gas pipelines, cablesystems such as electricity, telegraph, telephone and internet are in the concept oftransportation structures. There are many different features that must betaken intoaccount at design, construction and management phases aforementionedengineering structures. It is impossible to consider all of these features in thecontext of this course. Therefore, highways and railways will be considered,however, it is possible to use given information about geometric design and layoutfor other transportation structures.

3Engineering Surveying-Prof. Dr. Ergin TARI


GENERAL DEFINITIONSClassification of Highways: All of the roads can not be built atsame standards. They are classified according to certain parameters.These classifications are taken into account at determination ofdesign criterion (standards).

Classification parameters are;

1. habitation (urbanization) status

2. traffic volume

3. topography of the terrain



GENERAL DEFINITIONS1- Urbanization status:Highways are divided into two groups according to urbanization status; urbanroads and non-urban roads [KGM; 2005, s.8,9], [Müller; 1988, s.68,70].2- Traffic volume:Quality and quantity of the vehicles have an important role in determination ofroad standards. Annual average daily traffic or maximum hourly traffic aretakeninto account at design of the highways and amount of the future 15-20 years’traffic is estimated [Umar; Yayla; 1997, p.83-91].3-Topography of terrain: Topography of terrain is divided into three groups;plane, rough and mountainous. This classification is important at selecting designspeed. A highway can be constructed through these 3 types of terrain. But the class(classification) should not be changed frequently.A highway should also not be constructed from plane terrain to the mountainousterrain or in the opposite direction by neglecting the rough terrain.



GENERAL DEFINITIONSClassification of Railway: There are 4 types of railways according totopographic characteristic of the terrain; flat terrain railway, hilly terrainrailway, mountainous terrain railway and mountain railway[Evren;2002, s.14].

According to urbanization and transportation distance; intercity railway,suburban railway and urban railway can be a classification (tram, high speedtram, subway) [Evren; 2002, s.14].

There are different railway classifications; according totypes of trains that usethe railway;complex line (common route for passenger and freight train),passenger line; according to number of the trackssingle and double track;according to power source that provide motion;steam-operated, diesel,electrical; according to track width;normal line (aperture between rail axesis 1500 mm), wide and narrow line.



GENERAL DEFINITIONSDesign Speed (Vp): is a base speed for design criterion (geometricstandards) determination. Design speed for highways is defined in differentforms at various sources;

� [Umar; Yayla; 1997, s.81]: maximum safe speed without influence of other vehicles at normal weather conditions.

� [Kiper; 1988, s.11]: maximum safe speed at normal traffic flow and in normal weather conditions (including rainy weather).

� [Pietzsch; 1979, s.28]: maximum safe speed of %85 of the vehicles in case of normal traffic flow at clean and wet road without the lose of flow.



GENERAL DEFINITIONSDesign Speed Selection

A design speed is selected for each project which will establish criteria for severalgeometric design elements including horizontal and vertical curvature, superelevation, crosssectional features, and sight distance. In general, the selected design speed is based on thefollowing road design elements:

1. Functional Classification. The higher class facilities (i.e., arterials) are designed with ahigher design speed than the lower class facilities (i.e., collectors and locals).

2. Urban/Rural. Design speeds in rural areas are generally higher than those in urban areas. Thisis consistent with the typically fewer constraints in rural areas (e.g., less

development).

3. Terrain. The flatter the terrain, the higher the selected design speed can be. This isconsistent with the typically higher construction costs associated with more rugged terrain.

4. Traffic Volumes. On some facilities (e.g., unmarked rural collectors), the design speed

varies by traffic volumes; i.e., as traffic volumes increase, higher design speeds are used.



GENERAL DEFINITIONSDesign speeds according to road classes in Turkey [KGM; 2005,

p.7-9]

Road and Link Road (2x2)

Terrain class: Plain Rough Mountainous

Vp(km/h) : 120 100 80Urban road


Terrain Class Highway Urban Road

Multi Lane Two Lane Multi Lane Two Lane

Plain 100 60 90 60 80 60 70 50

Rough 80 60 80 60 70 50 60 30

Mountainous 80 60 60 50 60 40 60 30

TRANSPORTATION and TRANSPORTATION STRUCTURES – GENERAL DEFINITIONS

Non-urban road


Land Class Multilane

Road (2x2)

Two lane road

1.class 2.class 3.class 4.class

Plane PV ( km / s ) 100 90 100 80 80 70 70 60 50 40

Rough PV ( km / s ) 90 80 80 70 70 60 60 50 40 30

Highland PV ( km / s ) 80 60 70 60 60 40 50 30 30 20


Design speed is the maximum speed that can be safely applied atrailways and also calledtrack speed limit. This speed is used todetermine geometric standards for railways. In addition, applicablemaximum speed is defined considering locomotive traction,cooperload and operating conditions. This speed is used to plan theoperation [Evren; 2002, s.90-91].



Road Geometry: highway or railway is a narrow engineering structure thathas very large length compared to the width and forms a space surface. Thevertical (longitudinal) geometry of this surface is defined with route and thehorizontal geometry is defined withtypical cross sectionsand super-elevation.Route (Alignment): is a line belonging to road geometry that can be exactlydefined along the road.Route Definition for Highway: For divided roads; is axis of the central(island) reserve, for two-lane roads; if roadside shoulders has same width isplatform axis, if roadside shoulders has different width-pavement axis isselected as a route axis[Müller; 1988, s.86]. In the climbing lane and roadexpansion regions, only the main platform is taken into account.Route Definition for Railway: for single track railway is route axis, fordouble track railway; pavement axis is the route axis for therailway.



Figure 3.1: Intersection Points and Deviation Angle of Horizontal (Vertical) Route Geometry



Route Geometry: longitudinal geometry of the road is determined with thedesign of route geometry. Despite it is a space curve, route geometry is notdetermined with closed function such as f(x, y, z)=0. Horizontal and verticalroute geometry are designed separately [Müller, 1984, s.9].Horizontal Alignment: is designed with using line segment, arc and transitioncurves in respect to guidelines and design criterion. Superelevation andsuperelevation runoff are also designed in route geometry.The base map of theroute geometry is a large-scale (1/1000;1/2000) topographic map. DigitalTerrain Model (DTM) is used as a basis on computer aided design.Horizontal Intersection Point: is the breakpoint of two consecutive linesegments of the horizontal route geometry (Figure: 3.1). Despite lack ofcompliance with this definition, starting and end points ofthe route are alsoconsidered as a intersection point. While they are not a route point, intersectionpoints play very important role in the calculations.



Figure 3.2: Defining Point Chainage (Stationing) on Horizontal Route Geometry



Horizontal Deviation Angle: is an angle (∆i) between line segmentsat intersection points of horizontal route geometry (Figure 3.1). Thisangles are the main quantities of the horizontal geometrycomputations.

Distance from the origin-Km (Chainage-stationing): Thehorizontal distance measured through horizontal geometryfrom theselected beginning point to any point of the route. For example, atFigure 3.2; stationing of P is S0T1 line + T1T'1 curve + T'1T2 line +T2P curve. Distance from the origin is written in this form;

kmp = kilometer + meter, fractions of meter (14+038,673)



Chainage gives a unique identification of all highway points in amanner that is virtually equivalent to using true x, y, and zcoordinates.

In other words:

� Highways are measured along the centerline, rather than Cartesian coordinates.

� Stations are measured in km (there are also Imperial units for stationing) along a horizontal plane

� So 14+038,673 should be read as

10 kilometers and 38.673 meters from the point of origin on the roadway horizontally, which is at 0+000.000


TRANSPORTATION and TRANSPORTATION STRUCTURES – GENERAL DEFINITIONSMain Point, Detail Point: Connection points from one geometricelement to another on vertical and horizontal alignment of the roadcalled main points (beginning and end points of circular arc,transition curves, superelevation runoff (ramp)...etc.). Stationing ofthis points which are shown with different letters, computed withcalculation except some special cases.

Although it is shown as a continuous line at graphical design, layoutof the route cannot be done in the same way. The route must betransferred to the ground point by point. The frequency provided bymain points is extremely poor. So thedetail (intermediate) pointsstationing with the formula below are also transferred to the terrain.

kmPi = k∆l ; k = 1,2,3,...,n(with ∆l as 20, 25, 50 meters)(3.1)



During application projects, point densification maybe required in some parts of route with taken∆l=(5,10)m. In addition to those points, existingtransportation structures, watershed lines and intersectpoints are also called detail point. Stationing of thispoints is calculated by measuring horizontal distanceto a closest point with known stationing.



Direction of Horizontal Curvature: Direction of the curves on thehorizontal route geometry becomes important at computations.Direction of the curvature is defined with location of the curvaturecenter according to direction of the chainage increase. Curves arenamed as right curve (curve to right) or left curve (curve to left)according to this direction.Superelevation:Although transition curves can reduce the effect ofradial force on a vehicle this can also be further reduced or eveneliminated by raising one side (the one away from curve center) ofthe road relative to the other. The difference in height between thetwo sides of the road is known as the superelevation. In somesources, horizontal inclination of the road platform caused by theheight differences mentioned above, called superelevation [Umar,Yayla; 1997, s.136-137].



Vertical Alignment: is established with adding curves and line segments endto end considering guidelines and design criterion. Vertical route geometry isdesigned on the profile base.Profile: is the intersection of physical earth and vertical surfacesalong thehorizontal alignment of the road. Design of the horizontal route geometry andcomputations should be finished in order to create profile.Vertical Intersection Point: is the breakpoint of two consecutive linesegments of the vertical route geometry (Figure 3.1). Despite lack ofcompliance with this definition, starting and end points ofthe route are alsoconsidered as intersection points. Vertical intersectionpoints are representedwith U. Horizontal projection of any vertical intersectionpoint coincides withany route horizontal geometry point. Therefore, vertical intersection points hasstationing.Vertical Deviation Angle: is an angle between extension of consecutive linesegments(Figure 3.1). These angles are the main quantities(magnitudes) ofthe vertical geometry computations.



The horizontal and vertical alignments are not designed independently.

Instead they should complement each other. This is especially true for

new construction projects. Poorly coordinated designs can detract from

the benefits and emphasize the deficiency of each alignment.

Horizontal alignments and vertical profiles are among the most

important permanent design elements for a highway. Excellence in their

design and coordination increases the highway’s utility and safety,

encourages uniform speeds, and can greatly improve the highway’s

appearance. This usually can be accomplished with little additional costs.

The designer should coordinate the layout of the horizontal and vertical

alignment as early as practical in the design process. Alignment layouts are

typically completed after the topography and ground line have been

drafted. Computer visualization software are used to visualize how the

layout will appear in the field. Alternatives to ensure that the most pleasing

and practical design is selected.



Figure 3.3: Grade line, Ground line, Grade Elevationand Ground Elevation of Profile



Direction of Vertical Curvature: curvature direction of curve arcs on verticalroute geometry is very important. According to location of curve center, thereare 2 different types of vertical curves. If the center of thecurve directed to theground it is calledclosed curveor crest vertical curve; if the center directedto the sky it is calledopen curveor sag vertical curve [Umar; Yayla; 1997,s.168].

Center Line Point: Each of the horizontal alignment main and detail pointsthat has calculated layout elements and marked on the groundare called centerline [Umar; Yayla; 1997, s.113]. Stationing of the center line point is also thename of the point.

Cross Section: Sections that are perpendicular to the horizontal routegeometry. Stationing of the center line must be written on the cross sections.



Cross Section: Sections that are perpendicular to the horizontalroute geometry. Stationing of the center line must be written onthe cross sections.

A cross section is a vertical plane A cross section is a verticalplane (slice) taken at right angles to the road control lineshowing the various control line showing the various elementsthat make up the roads structure..

It is normally viewed in the direction of increasing chainage.



Ground Elevation: is the elevation of center line points (for profile) andcharacteristic points of natural terrain (for cross section). Ground elevationshows natural topographic characteristics of the terrain (Figure 3.3)

Ground Line: is obtained by combining sequential points of known groundelevation with line segments (Figure 3.3 and 3.4). Ground line shows naturalcharacteristic of terrain graphically along profile and cross section route.


Grade (Project) Elevation: is the design elevation of the vertical routegeometry points on the profile base. It is determined with computation (Figure3.3).

Grade (Project) Line: is the graphical visualization of vertical route geometrydesigned on profile (Figure 3.3). Grade and ground elevation of any P point isobtained from vertical route geometry (Figure 3.3). With known grade andground elevation, typical cross section is transferred to cross sections of P.Thus, grade line is obtained on cross sections (Figure 3.4).Grade elevation ofthe cross section points is determined with computation.

Typical Cross Section: is a section that represents horizontal and verticalgeometry of transportation structure which is perpendicular to horizontal routegeometry without superelevation [Evren; 2002, s.129], [Müller, 1984, s.206].



While obtaining grade line (project line) of cross section,superelevationapplication must be taken into account on horizontal alignment. Generally,one type cross section is not enough along the transportation structures.Special cross section types are used at; subways, climbing line sections of thehighways, high level excavation and fills require retaining wall, bridges andculverts…etc.

Typical cross section represents; inclination of embankment slope andexcavation slope, size of bottom, interception and side ditch, divided roads,number of lanes, width of shoulders, pavement and central (island) reserve,number of railway lines, line width and distance between line axis…etc.Typical cross section is one of the main elements of transportation structurestandards determination and must be considered with designspeed.




Figure 3.4: Grade line, Ground line and other Definitions of Cross-Section


Earthwork: Closed areas created by grade line and ground line of profiles andcross-sections show the necessary earthwork. Filling-excavation must be donein the areas where grade (project) heights are smaller-bigger than groundheights.

Complex Cross-section: Cross-section that has both filling area andexcavation (cut) area.

Girder Cross-section:Cross-section that has only cut area.

Cut and Fill Slope: Inclined surface created between the road and the territoryat the end of the earthwork.

Side ditch: Ditch that provides the drainage of rain water fall to the cutslopeand the road surface.



Interception Ditch: created ditch when needed at junction point ofescarpment and territory (Figure 3.4).

Bottom Ditch: applied at junction point of fill slope and territory. The aim ofthe bottom ditch is to prevent the collapse the bottom of fillslope due torainwater (Figure 3.4).

Relocation, Variant: certain part of the horizontal geometry need to bechanged at the end of the route horizontal geometry design and route verticalgeometry design in parallel with this route horizontal geometry. Relocation isthe horizontal geometry changes within the cross-sections. Variant is thehorizontal geometry changes out of the cross-sections. Profiles and cross-sections must be updated at variant, but they are not updatedat relocation.



32Engineering Surveying-Prof. Dr. Ergin TARItranslated by Res. Assist. Serpil ATEŞ

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